Diabetes mellitus and serum organochlorine pesticides mixtures in Mexican women.

BACKGROUND: Very recently, it has been reported that exposure to different mixtures of organochlorine pesticides (OCP) is associated with the development of diabetes mellitus (DM). In Mexico, DM is a public health problem that might be related to the historical intense use of OCP. We aimed to evaluate, the association between DM and serum concentrations of OCP mixtures, and identify the main contributors within them. METHODS: We conducted a secondary cross-sectional analysis on the control group from a breast cancer population-based case-control study conducted from 2007 to 2011 in Northern Mexico. We identified 214 self-reported diabetic women and 694 non-diabetics. We obtained direct information about sociodemographic, lifestyle and reproductive characteristics. We determined 24 OCP and metabolites in serum by gas chromatography using an electron capture micro detector. We used Weighted Quantile Sum regression to assess the association of DM and exposure to multiple OCP, and the contribution of each compound within the mixture. RESULTS: We found a positive adjusted association between DM and an OCP mixture (OR: 2.63, 95%CI: 1.85, 3.74), whose primary contribution arose from p, p'-DDE (mean weight 23.3%), HCB (mean weight 17.3%), trans nonachlor (mean weight 15.4%), o, p'-DDE (mean weight 7.3%), heptachlor epoxide (mean weight 5.9%), oxychlordane (mean weight 4.7%), and heptachlor (mean weight 4.5%). In addition, these OCP along with p, p'-DDT and cis chlordane, were of concern and remained associated when excluding hypertensive women from the analysis (OR 2.55; 95% CI 1.56, 4.18). CONCLUSIONS: Our results indicate, for the first time in a Latin-American population, that the concomitant exposure to multiple OCP is associated with DM. Further research is needed since the composition of OCP mixtures may vary according to regional pesticides use patterns.

Carcinogenic, non-carcinogenic risk, and attributable cases to organochlorine pesticide exposure in women from Northern Mexico.

This study aimed to estimate the carcinogenic and non-carcinogenic risk as well as the attributable cases due to exposure to organochlorine pesticides (OCPs): hexachlorobenzene (HCB), dichlorophenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), heptachlor, and chlordane. From serum concentrations of pesticides of interest in a sample of 908 women from Northern Mexico, the risk for both cancer and non-cancer health effects was evaluated. The population attributable fraction (PAF) was also calculated based on summary association estimates between exposure to OCPs and different health events. Findings revealed that due to their OCP exposure slightly less than half of the women in the sample were at increased risk of developing non-cancerous diseases. Moreover, approximately 25% and 75% of participants were at risk of develop some type of cancer associated with their HCB and DDE concentrations, respectively. In addition, it was estimated that 40.5% of type 2 diabetes, 18.7% of endometriosis, and 23.1% of non-Hodgkin's lymphoma cases could have been prevented if women had not been exposed to these OCPs. Results suggest that the use of OCPs may have contributed to the disease burden in the study area and, based on the time required for these substances to be eliminated from the body, there are probably some women who are still at elevated risk of developing diseases associated to OCPs.

Epidemiology of childhood acute leukemias in marginalized populations of the central-south region of Mexico: results from a population-based registry.

Introduction: Acute leukemias (AL) are the main types of cancer in children worldwide. In Mexico, they represent one of the main causes of death in children under 20 years of age. Most of the studies on the incidence of AL in Mexico have been developed in the urban context of Greater Mexico City and no previous studies have been conducted in the central-south of the country through a population-based study. The aim of the present work was to identify the general and specific incidence rates of pediatric AL in three states of the south-central region of Mexico considered as some of the marginalized populations of Mexico (Puebla, Tlaxcala, and Oaxaca). Methods: A population-based study was conducted. Children aged less than 20 years, resident in these states, and newly diagnosed with AL in public/private hospitals during the period 2021-2022 were identified. Crude incidence rates (cIR), standardized incidence rates (ASIRw), and incidence rates by state subregions (ASIRsr) were calculated. Rates were calculated using the direct and indirect method and reported per million children under 20 years of age. In addition, specific rates were calculated by age group, sex, leukemia subtype, and immunophenotype. Results: A total of 388 cases with AL were registered. In the three states, the ASIRw for AL was 51.5 cases per million (0-14 years); in Puebla, it was 53.2, Tlaxcala 54.7, and Oaxaca de 47.7. In the age group between 0-19 years, the ASIRw were 44.3, 46.4, 48.2, and 49.6, in Puebla, Tlaxcala, and Oaxaca, respectively. B-cell acute lymphoblastic leukemia was the most common subtype across the three states. Conclusion: The incidence of childhood AL in the central-south region of Mexico is within the range of rates reported in other populations of Latin American origin. Two incidence peaks were identified for lymphoblastic and myeloid leukemias. In addition, differences in the incidence of the disease were observed among state subregions which could be attributed to social factors linked to the ethnic origin of the inhabitants. Nonetheless, this hypothesis requires further investigation.

Exposure to p,p´-DDE during early pregnancy, anthropometry, and gestational age at birth, in a flower-growing region of Mexico.

Prenatal exposure to dichlorodiphenyldichloroethylene (p,p´-DDE) may interfere with fetal development; however, studies evaluating anthropometry and gestational age at birth show inconsistent results. Typically, p,p´-DDE exposure has been measured during the third trimester and missed the key early pregnancy period. We evaluated the association between p,p´-DDE exposure before week 18 of pregnancy and anthropometry at birth, as well as gestational length, in 170 mother-child pairs from a cohort study in a flower-growing mexican region. Maternal serum p,p´-DDE concentrations were determined by gas chromatography. The associations between p,p´-DDE and z-scores of birth weight, birth length, and gestational age were evaluated by linear multiple regression models. Logistic regression models were used for low birth weight and small size for gestational age. Effect modification by child's sex was explored. The average gestational age at the blood sample extraction was 10.6 weeks. p,p'-DDE was detected in 64.7% of mothers, at a geometric mean of 0.24 ng/mL. Prenatal p,p´-DDE exposure was not associated with the birth outcomes in the whole sample. However, a high p,p´-DDE exposure was marginally associated with greater small for gestational age risk in male newborns (OR≥0.076ng/mL vs <0.076 ng/mL = 3.09, 95% CI: 0.61; 15.58), but not in female (p for interaction = 0.08).Even though, we found no reductions in anthropometric measurements or gestational length associated with early prenatal p,p´-DDE exposure, the potential effect modification by infant's sex in terms of small for the gestational age risk deserves future studies.

Metal exposure and breast cancer among Northern Mexican women: assessment of genetic susceptibility.

This study aims to assess breast cancer (BC) association with metals and whether polymorphisms in CYP1A1, CYP1B1, GSTM1 and GSTT1 act as confounders or as modifiers of those relationships. We performed a secondary analysis of 499 histologically confirmed BC cases and the same number of age-matched population controls. We measured urinary concentrations of 18 metals with mass spectrometry. We determined the genetic variants of interest by allelic discrimination and multiplex PCR. After adjusting for covariates, we found BC negatively associated with arsenic, barium, cobalt, copper, magnesium, molybdenum and vanadium concentrations and positively with those of caesium, manganese, tin and thallium. Most associations remained after stratifying by the genetic variants. We identified that polymorphisms in CYP1B1, CYP1A1 and GSTM1 genes interacted with some metals on BC: interaction p-values CYP1B1 G119T × antimony= 0.036, CYP1B1 G119T × cobalt <0.001, CYP1B1 G119T × tin= 0.032, CYP1A1 A4889G × aluminium= 0.018, CYP1A1 A4889G × arsenic= 0.031, CYP1A1 A4889G × nickel= 0.036, CYP1A1 A4889G × vanadium= 0.031 and GSTM1 deletion × barium= 0.035. Exposure to various individual metals, along with genetic characteristics may contribute to BC development. Further studies are warranted to confirm our results.

Breast cancer and urinary metal mixtures in Mexican women.

Humans are environmentally exposed to many metals throughout their lives. Simultaneous exposure to several metals could result in synergistic or antagonistic toxicological effects among them; however, the information on exposure to mixtures of metals and breast cancer (BC) is scarce. The objective of this report was to compare metals considered human carcinogens, individually and as mixtures, in women with and without BC. This is a secondary analysis of a population-based case-control study that was carried out from 2007 to 2011 in Northern Mexico. A total of 499 histologically confirmed BC cases and 499 controls were included. Information about sociodemographic, lifestyle and reproductive characteristics was obtained by in-person interviews. Urinary concentrations of aluminum (Al), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), antimony (Sb), cobalt (Co), molybdenum (Mo), tin (Sn), and vanadium (V) were determined by inductively coupled plasma triple quadrupole. Metal mixtures were identified by principal component analysis with creatinine-corrected metals. Over 90% of subjects had metal measurements above the detection limit except tin (86%) and antimony (78.4%). After adjusting by selected covariables, we observed that the individual urinary concentrations of V, Co, and Mo were lower among cases compared to controls; in contrast to Sn that had higher concentrations. We identified two principal component mixtures with opposite relationships with BC: Cr, Ni, Sb, Al, Pb and Sn (OR = 1.15; CI95% 1.06,1.25) and Mo and Co (OR = 0.56; CI95% 0.49,0.64). This is the first study that identified urinary metal mixtures that differed between women with and without BC. Our results warrant confirmation in further prospective epidemiological studies. In addition, the elucidation of underlying mechanisms of metal interactions on BC risk deserves further research.

Prevalence of type 2 diabetes mellitus in relation to arsenic exposure and metabolism in Mexican women.

BACKGROUND: Experimental studies have shown the diabetogenic potential of inorganic arsenic (iAs); however, the epidemiological evidence is still inconclusive. This could be explained by differences in exposure, metabolism efficiency, nutritional and genetic factors. OBJECTIVE: To evaluate the association between type 2 diabetes mellitus (T2DM) prevalence with arsenic exposure and metabolism, considering one-carbon metabolism nutrient intake and arsenite methyltransferase (AS3MT) polymorphisms. METHODS: From healthy controls of a case control study for female breast cancer in northern Mexico, 227 self-reported diabetic women were age-matched with 454 non-diabetics. Participants were interviewed about dietary, sociodemographic and clinical characteristics. Urinary iAs metabolites were determined by HPLC-ICP-MS, methylation efficiency parameters were calculated, and AS3MT c.860 T > C and c.529-56G > C genotypes were determined. Unconditional logistic regression models were used to evaluate associations. RESULTS: Total arsenic in urine (TAs) ranged from 0.73 to 248.12 µg/L with a median of 10.48 µg/L. In unadjusted analysis, TAs (µg/g) was significantly higher in cases than controls, but not when expressed as TAs (µg/L). Cases had significantly lower urinary monomethylarsonic acid percentage (%MMA), first methylation ratio (FMR), creatinine, and choline and selenium intakes. In multi-adjusted models and in women without HTA history T2DM showed significant positive associations with %iAs and FMR, respectively, and a significant negative association with %DMA. In participants with HTA history there was a marginal positive association (p = 0.08) between T2DM and TAs concentrations (µg/g) without other significant associations. CONCLUSIONS: Our results support an association between T2DM prevalence and iAs metabolism but not with urinary arsenic levels. However, elucidation of the interplay among iAs metabolism, T2DM and HTA merit further studies.

Epidemiologic evidence of exposure to polycyclic aromatic hydrocarbons and breast cancer: A systematic review and meta-analysis.

Breast cancer (BC) is the most frequently diagnosed cancer in women. However, only 58% of cases have been associated with known risk factors (reproductive, hormonal, lifestyles, and genetic), and the rest to unknown causes. Nevertheless, growing evidence suggests that exposure to environmental contaminants is an important risk factor for BC. Polycyclic aromatic hydrocarbons (PAHs) are formed during organic matter combustion, including smoking, grilled meat, and fuels, and are important carcinogenic constituents of environmental pollution. We examined the information generated by epidemiological studies evaluating the association between BC and PAHs exposure from multiple sources. Our work was conducted according to Conducting Systematic Reviews and Meta-Analyses of Observational Studies of Etiology (COSMOS-E) guidelines. We searched PubMed, Web of Science, and Scopus from January 2000 to December 2019. A total of 124 records were identified, and only 23 articles met all inclusion criteria. Occupational and/or environmental exposure to PAHs was significantly associated with BC, irrespective of exposure being assessed by direct or indirect methods. CYP1A1 and CYP1B1 adverse polymorphisms, familial BC history and smoking status, significantly strengthened the association between PAHs exposure and BC, whereas high fruit and vegetable intake had antagonistic associations. The positive relationships obtained in the studies here reviewed indicated that PAHs exposure is a risk factor for BC. Research needs include the improvement of exposure assessment, particularly identification of specific PAHs, reconstruction of time-varying and distant past exposures and further studies on the interaction between known BC factors and modifiable diet and life-style factors allowing BC prevention and control.

Dietary fiber intake and urinary creatinine: methodological implications for epidemiological studies.

Creatinine values are used to estimate renal function and to correct for urinary dilution in exposure assessment studies. Interindividual variability in urinary creatinine (UCR) is determined positively by protein intake and negatively by age and diabetes. These factors, among others, need to be accounted for, to increase comparability throughout epidemiological studies. Recently, dietary fiber has been shown to improve renal function. This study aims to evaluate dietary fiber intake relationship with UCR and its methodological implications for studies using UCR-corrected measurements. In a cross-sectional study, we analyzed information regarding UCR, dietary fiber, age, and other UCR-related factors in 801 women residing in Northern Mexico during 2007-2009. The median fiber intake in this population was 33.14 g/day, above the adequate intake level for women > 18 years. We estimated an age-adjusted increase of 10.04 mg/dL UCR for a 10 g/day increase in dietary fiber intake. The main dietary sources of fiber in this population were corn tortillas, raw onions, flour tortillas, and beans. Our results suggest that epidemiological studies adjusting analytes by UCR should also consider controlling dietary fiber intake to improve the comparability of creatinine-corrected values and associations across different populations, such as those in Mexico and Latin America, where protein and fiber intake vary significantly.

Physical activity, body mass index and arsenic metabolism among Mexican women.

BACKGROUND: In some epidemiological studies, a positive association of body mass index (BMI) with inorganic arsenic (iAs) metabolism parameters (percentage dimethylarsinic acid [%DMA] and secondary methylation index [SMI]) has been found. In iAs metabolism, S-Adenosyl methionine is converted to S-Adenosyl homocysteine. Sedentarism has been associated with a higher risk of hyperhomocysteinemia. Physical activity has shown an inconsistent negative association with BMI. Therefore, our objective was to evaluate whether physical activity is associated to iAs metabolism independently of BMI. METHODS: We performed a cross-sectional secondary analysis on 800 non-diabetic women, ≥18 years, who participated as population controls in a previous study on breast cancer in northern Mexico. Participants were interviewed about physical activity during their lifetime, and their weight and size were obtained. Urinary arsenic metabolites concentrations were determined by high performance liquid chromatography coupled with mass spectrometry. RESULTS: In the study population, total arsenic ranged from 0.71 to 303.29 µg/L, and the lifetime average physical activity from 0 to 788.40 min/week. BMI was significantly and negatively associated with percentage monomethylarsonic acid (%MMA) and primary methylation index (PMI), and positively associated with %DMA, SMI and TMI, respectively. Likewise, physical activity was negatively associated with %iAs and %MMA, and positively associated with %DMA, SMI and TMI. These results remained after BMI was adjusted for physical activity and viceversa. CONCLUSION: This study confirms the relationship between BMI and iAs metabolism parameters and provides new evidence on the association between physical activity and iAs metabolism.

Arsenic exposure in northern Mexican women.

OBJECTIVE: To describe interindividual metabolism variations and sociodemographic characteristics associated to urinary arsenic, and to estimate the arsenic contamination in water from urinary total arsenic (TAs). MATERIALS AND METHODS: Women (n=1 028) from northern Mexico were interviewed about their sociodemographic characteristics and their urinary concentrations of arsenic species were measured by liquid chromatography. Inorganic arsenic (iAs) in water was estimated from urinary TAs. RESULTS: Women were 20-88 years old. TAs in urine ranged from p10=3.41 to p90=56.93 µg/L; 74% of women had levels >6.4 µg/L. iAs in water varied from p10=3.04 to p90=202.12 µg/L; 65% of women had concentrations >10 µg/L, and 41%, concentrations >25 µg/L. Large variations in iAs metabolism were observed. TAs was significantly negatively associated with age and schooling, and positively with the state of residence. CONCLUSIONS: Exposure to iAs is an environmental problem in Mexico. Individual variations in metabolism are a challenge to design prevention and control programs.

OBJETIVO: Describir las variaciones interindividuales del metabolismo y las características sociodemográficas asociadas con el arsénico urinario, así como estimar su contaminación en el agua. MATERIAL Y MÉTODOS: Se entrevistó a 1 028 mujeres del norte de México; por cromatografía de líquidos se midieron los metabolitos urinarios de arsénico y, a partir de ellos, se estimó la concentración en agua. RESULTADOS: Las mujeres tuvieron 20-88 años. El arsénico urinario varió de p10=3.41 a p90=56.93 µg/L; 74% de las mujeres tuvieron niveles >6.4 µg/L. El arsénico en agua varió de p10=3.04 a p90=202.12 µg/L; 65% de las mujeres tenían concentraciones >10 µg/L, y 41%, >25 µg/L. Se observaron amplias variaciones en el metabolismo del arsénico. El arsénico urinario se asoció negativamente con la edad y escolaridad, y positivamente con el estado de residencia. CONCLUSIONES: La exposición a arsénico es un problema ambiental en México. Las variaciones individuales en su metabolismo son un desafío para diseñar programas de prevención y control.

Arsenic exposure in northern Mexican women / Exposición a arsénico en mujeres del norte de México

Abstract: Objective: To describe interindividual metabolism variations and sociodemographic characteristics associated to urinary arsenic, and to estimate the arsenic contamination in water from urinary total arsenic (TAs). Materials and methods: Women (n=1 028) from northern Mexico were interviewed about their sociodemographic characteristics and their urinary concentrations of arsenic species were measured by liquid chromatography. Inorganic arsenic (iAs) in water was estimated from urinary TAs. Results: Women were 20-88 years old. TAs in urine ranged from p10=3.41 to p90=56.93 μg/L; 74% of women had levels >6.4 μg/L. iAs in water varied from p10=3.04 to p90=202.12 μg/L; 65% of women had concentrations >10 μg/L, and 41%, concentrations >25 μg/L. Large variations in iAs metabolism were observed. TAs was significantly negatively associated with age and schooling, and positively with the state of residence. Conclusion: Exposure to iAs is an environmental problem in Mexico. Individual variations in metabolism are a challenge to design prevention and control programs.

Resumen: Objetivo: Describir las variaciones interindividuales del metabolismo y las características sociodemográficas asociadas con el arsénico urinario, así como estimar su contaminación en el agua. Material y métodos. Se entrevistó a 1 028 mujeres del norte de México; por cromatografía de líquidos se midieron los metabolitos urinarios de arsénico y, a partir de ellos, se estimó la concentración en agua. Resultados: Las mujeres tuvieron 20-88 años. El arsénico urinario varió de p10=3.41 a p90=56.93 μg/L; 74% de las mujeres tuvieron niveles >6.4 μg/L. El arsénico en agua varió de p10=3.04 a p90=202.12 μg/L; 65% de las mujeres tenían concentraciones >10 μg/L, y 41%, >25 μg/L. Se observaron amplias variaciones en el metabolismo del arsénico. El arsénico urinario se asoció negativamente con la edad y escolaridad, y positivamente con el estado de residencia. Conclusión: La exposición a arsénico es un problema ambiental en México. Las variaciones individuales en su metabolismo son un desafío para diseñar programas de prevención y control.

Inorganic arsenic methylation capacity and breast cancer by immunohistochemical subtypes in northern Mexican women.

BACKGROUND: Previously we reported that inorganic arsenic (iAs) methylation capacity was associated with breast cancer (BC). BC risk factors may vary according to immunohistochemical subtype. Here we explored the relationships between the capacity to methylate iAs and the risk of BC by subtype. METHODS: A population-based case-control study was performed in northern Mexico. Patients with available information about BC subtypes (n = 499) were age-matched with healthy controls. Sociodemographic, reproductive, and lifestyle characteristics were obtained. Tumor marker information was obtained from medical records. Cases were classified as HR+ [estrogen receptor (ER+) and/or progesterone (PR+), and human epidermal growth factor receptor 2 (HER2-)], HER2+, or triple negative (TN). Urinary arsenic species were determined by high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS), and methylation capacity parameters calculated. Conditional logistic regression models were used to estimate BC risk by subtypes. RESULTS: Urinary total arsenic varied from 0.60 to 303.29 µg/L. A significant positive association was found between % monomethylarsonic acid (%MMA) and HR + BC: one percent increase resulted in OR%MMA continuous = 2.73, 95% CI: 1.48, 5.05), and this association remained even when %iAs or % dimethylarsinic acid (%DMA) were added to the models with %MMA. MMA/iAs was positively associated with HR + BC (ORMMA/iAs continuous = 2.03, 95% CI: 1.33-3.10). A significant negative association was observed between DMA/MMA and HR + BC (ORDMA/MMA continuous = 0.43, 95% CI: 0.26, 0.71). MMA/iAs was positively associated with TN BC (OR MMA/iAs continuous = 4.05; 95% CI: 1.63, 10.04). CONCLUSION: Altered iAs methylation capacity resulting in higher %MMA was associated with HR+ and TN BC but not with HER2+. MMA is the iAs metabolite more likely to be related to BC. Further research is needed to confirm these results and elucidate the underlying biological mechanisms.

A cumulative index of exposure to endogenous estrogens and breast cancer by molecular subtypes in northern Mexican women.

PURPOSE: To evaluate breast cancer (BC) molecular subtypes association with reproductive characteristics and an index of cumulative exposure to endogenous estrogens (EEI) in Mexican women. METHODS: We performed a study of incident cases and population controls in northern Mexico. We included BC cases with tumor molecular classification in their medical records (n = 509), and classified them as HR+/HER2- (ER+ and/or PR+ and HER2-) (n = 289), HER2+ (HR+ or HR-) (n = 117) or triple negative (TN) (n = 103). We matched controls (n = 1030) by age and place of residence with index cases. Women were interviewed about their reproductive history, from which the EEI was developed. We used logistic regression models to estimate BC molecular subtypes associations with reproductive characteristics and EEI. RESULTS: The EEI was higher in all subtypes compared to controls (Median HR+/HER2- 27.25, HER2+ 26.8, TN 24.2 vs. controls 22.8 years, p < 0.05), and was associated with HR+/HER2- (ORT3 vs. T1 = 2.58, 95% CI 1.77-3.55, p-trend < 0.001) and HER2+ (ORT3 vs. T1 = 4.17, 95% CI 2.15-8.08, p-trend < 0.001) BC. Additionally, HR+/HER2- tumors were positively associated with age at first pregnancy and age at menopause, and negatively with age at menarche, parity and breastfeeding. The HER2+ subtype was associated in the same direction as HR+/HER2- tumors with all the reproductive characteristics except for age at menarche. TN tumors were negatively associated with parity and breastfeeding. CONCLUSION: Endogenous estrogens exposure throughout Mexican women reproductive life may contribute to the development of all but TN BC, however, these findings should be confirmed in other Hispanic populations.

Challenges to regulate products containing bisphenol A: Implications for policy.

Bisphenol A (BPA), found in plastics and epoxy resins, is one of the most studied chemicals. BPA is regarded as an endocrine disruptor and has been related to adverse health effects in humans. However, some regulatory agencies around the world have concluded that BPA is safe at current human exposure levels. As the scientific community attempts to settle the debate on BPA's health effects, regulatory agencies have been put into a challenging public health policy situation. The United States has implemented no regulatory actions due to safety concerns, while Europe has used the precautionary principle to guide its regulation in the face of scientific uncertainty. In this paper, we explore the debate surrounding BPA regulation and the possibility for countries to introduce guidelines, using Mexico as an example. Policy change determinants analysis suggest that countries can and should impose regulations on BPA.

El bisfenol A (BPA), presente en plásticos y resinas epoxi, es uno de los químicos más estudiados. Se considera un disruptor endocrino y se ha relacionado con efectos adversos para la salud humana. Algunas agencias regulatorias en el mundo han concluido que el BPA es seguro a los niveles de exposición humana actuales. Mientas la comunidad científica intenta resolver el debate sobre dichos efectos, las agencias regulatorias enfrentan una difícil situación de política pública. Los Estados Unidos de América no han implementado acciones reglamentarias por razones precautorias, mientras que Europa ha utilizado el principio precautorio para guiar su regulación ante la incertidumbre científica. En este documento exploramos el debate que rodea la regulación del BPA y la posibilidad de que los países introduzcan directrices, usando a México como ejemplo. El análisis de los determinantes del cambio de políticas sugiere que los países pueden y deben regular el BPA.

Challenges to regulate products containing bisphenol A: Implications for policy / Desafíos para regular los productos que contienen bisfenol A: implicaciones para la política

Abstract: Bisphenol A (BPA), found in plastics and epoxy resins, is one of the most studied chemicals. BPA is regarded as an endocrine disruptor and has been related to adverse health effects in humans. However, some regulatory agencies around the world have concluded that BPA is safe at current human exposure levels. As the scientific community attempts to settle the debate on BPA's health effects, regulatory agencies have been put into a challenging public health policy situation. The United States has implemented no regulatory actions due to safety concerns, while Europe has used the precautionary principle to guide its regulation in the face of scientific uncertainty. In this paper, we explore the debate surrounding BPA regulation and the possibility for countries to introduce guidelines, using Mexico as an example. Policy change determinants analysis suggest that countries can and should impose regulations on BPA.

Resumen: El bisfenol A (BPA), presente en plásticos y resinas epoxi, es uno de los químicos más estudiados. Se considera un disruptor endocrino y se ha relacionado con efectos adversos para la salud humana. Algunas agencias regulatorias en el mundo han concluido que el BPA es seguro a los niveles de exposición humana actuales. Mientas la comunidad científica intenta resolver el debate sobre dichos efectos, las agencias regulatorias enfrentan una difícil situación de política pública. Los Estados Unidos de América no han implementado acciones reglamentarias por razones precautorias, mientras que Europa ha utilizado el principio precautorio para guiar su regulación ante la incertidumbre científica. En este documento exploramos el debate que rodea la regulación del BPA y la posibilidad de que los países introduzcan directrices, usando a México como ejemplo. El análisis de los determinantes del cambio de políticas sugiere que los países pueden y deben regular el BPA.

Exposure to bisphenol A and diabetes risk in Mexican women.

Bisphenol A (BPA) is an endocrine-disrupting chemical widely used in the production of polycarbonate plastics and epoxy resins, which has been previously linked to diabetes among non-Hispanic populations. As part of a case control study for breast cancer, only controls with BPA information were included in this report. The final sample size comprises 70 self-reported diabetics and 334 non-diabetics. Urinary free bisphenol A (BPA-F) (µg/L) was determined by solid-phase extraction and HPLC/FLD analysis. Logistic regression models were used to evaluate the association between BPA-F and self-reported diabetes. After adjusting by age, urinary BPA-F (4.06-224.53 µg/g creatinine) was associated with diabetes exposure (OR = 1.85; 95% CI 1.04, 3.28) compared with women in the reference category (0.67-4.05 µg/g creatinine). BPA may be an environmental cofactor of diabetes. More studies are needed to confirm this result, especially in Hispanic populations.

Polyunsaturated fatty acids and child neurodevelopment among a population exposed to DDT: a cohort study.

BACKGROUND: Child neurodevelopment has been positively linked to maternal intake of polyunsaturated fatty acids (PUFAs) during pregnancy; however, it is unknown if that relationship persists among populations exposed to environmental neurotoxicants. OBJECTIVE: The aim of this work was to assess whether maternal dietary intake of PUFAs during pregnancy is positively associated with child neurodevelopment, whose mothers were environmentally exposed to 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT). METHODS: A prospective cohort study with 276 mother-child pairs was performed in Mexico. Neurodevelopment was assessed by Bayley Scales II from children age 1 to 30 months. Dietary PUFAs intake was estimated by Food Frequency Questionnaire at 1st and 3rd trimester of pregnancy. DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene, the main metabolite of DDT) maternal serum levels were determined by electron capture gas chromatography. Longitudinal multivariate linear mixed-effects analysis, which combines mental (MDI) and motor (PDI) Bayley scales in a single model, were performed. RESULTS: Our results show that in a sample environmentally exposed to DDT, maternal ingestion of DPA during the first trimester of pregnancy was positively associated with MDI (ß = 0.10, 95% CI 0.02, 0.18) in children from 1 to 30 months. Likewise, our results suggest that dietary ALA may be also related to MDI. CONCLUSION: DPA may benefit neurodevelopment even in populations exposed to DDT. Our results strengthen the importance of PUFAs intake during the prenatal period.

Effects of ALAD genotype on the relationship between lead exposure and anthropometry in a Cohort of Mexican children.

OBJECTIVES: Lead exposure is associated with children's growth, but this relationship may depend on the presence of susceptibility factors, including genetic variation. Blood lead levels (BLL) differ by ALAD (aminolevulinic acid dehydratase) genotype. We investigated the association between BLL and growth in Mexican first-graders with different ALAD genotypes. METHODS: Children between the ages of 6-8 years (n = 602) attending first grade in schools within the vicinity of a metal foundry in Torreón, Mexico were enrolled into a randomized controlled trial (RCT) testing the efficacy of iron and/or zinc supplementation on blood lead levels (BLL) and cognition. BLL and anthropometry were assessed at baseline (height, height-for-age z-score (HAZ), knee height, head circumference), after 6 (head circumference) and 12 months (height, HAZ, knee height). Children with ALAD1-1 and ALAD1-2/2-2 were compared. The study sample included 538 and 470 participants who had complete data at baseline and follow-up, respectively. Separate multivariable linear regression models adjusted for covariates were used to test the association between BLL at baseline and each anthropometric measure. Covariates included age, sex, hemoglobin, crowding, and maternal education. BLL x ALAD genotype interaction term was tested. RESULTS: Median BLL (10.1 µg/dL) did not differ by ALAD genotype. After covariate adjustment, baseline BLL was inversely associated with baseline height, HAZ, and knee height. The association (ß [95% CI]) between BLL and baseline height (-0.38[-0.68, -0.09]), HAZ (-0.07[-0.12, -0.02]) and knee height (-0.14[-0.25, -0.02]), was somewhat stronger in children with ALAD1-2/2-2 than ALAD1-1 (-0.09[-0.16, -0.02], -0.02[-0.03, -0.004] and -0.04[-0.06, -0.01], respectively). No associations between BLL and growth at 6 or 12 months were detected irrespective of ALAD genotype. CONCLUSIONS: BLL was adversely associated with anthropometric measures among Mexican children. ALAD genotype may be a susceptibility factor for the effects of lead on child growth.

Dietary flavonoids improve urinary arsenic elimination among Mexican women.

Inorganic arsenic (iAs) exposure increases risk of several diseases, including cancer. Some nutrients such as flavonoids enhance glutathione activity, which in turn play a key role in iAs elimination. Our objective was to explore whether dietary non-soy flavonoids are associated with iAs metabolism. We hypothesized that the intake of flavonoids belonging to the following groups, flavan-3-ols, flavone, flavonol, flavanone, and anthocyanidin, is positively associated with urinary dimethylarsinic acid (DMA), which is the most soluble iAs metabolite excreted. We performed a cross-sectional study that included 1027 women living in an arsenic-contaminated area of northern Mexico. Flavonoid intake was estimated using a validated food frequency questionnaire. Concentration of urinary iAs and its metabolites (monomethylarsonic acid and DMA) were determined by high performance liquid chromatography ICP-MS. Results showed positive significant associations between DMA and the flavonoid groups flava-3-ols (ß= 0.0112) and flavones (ß= 0.0144), as well as the individual intake of apigenin (ß= 0.0115), luteolin (ß= 0.0138), and eriodictyol (ß= 0.0026). Our findings suggest that certain non-soy flavonoids may improve iAs elimination; however, there is still very limited information available regarding the consumption of flavonoids and iAs metabolism.